This application is for partial support of a small, international symposium on "Invariance and Variability of Speech Processes" to be held at M.I.T. on October 8-10, 1983. The symposium is being organized by members of the Speech Communication Group, Research Laboratory of Electronics at M.I.T. and Professors from the Royal Institute of Technology and Stockholm University in Stockholm. In spite of the scientific and technological advances which have been made in the past 30 years of speech research, we still are far from having a theory of speaking and listening that satisfactorily integrates observations concerning the linguistics, psychology, phsiology and physics of speech behavior. The lack of such a theory is seen as a stumbling block in the efforts of speech researchers to meet human and social needs, and some of the most difficult problems in the quest for this theory revolve around the issues of invariance and variability. Variability may be the finding which most universally characterizes speech processes. Variability arises from a number of poorly-understood sources, and it confounds the search for invariant aspects of the speech code. On the other hand, certain kinds of evidence, along with the underlying nature and information-transmitting function of speech argue compellingly for the existence of invariant units and for continued research in this area. Views on invariance and variability in speech differ widely, depending on the discipline; therefore, an interchange of ideas from different viewpoints should be very helpful in clarifying our understanding of this issue. To this end, about 60 leading research workers from the fields of speech production, perception, acoustics, pathology, psychology, linguistics, language acquisition, synthesis and recognition have been invited to participate. There will be 6 half-day sessions, each with one or two keynote papers representing a particular viewpoint and several comments on the keynote papers. All papers will be prepared and distributed in draft form in advance of the meeting, providing an opportunity for a genuinely fruitful interaction. Manuscripts will be revised and edited for publication following the symposium.